In the case of a triple gripper weaving machine for carpet or velvet it is expedient first to insert one weft thread in the top fabric and two weft threads in the bottom fabric simultaneously, and then to insert two weft threads in the top fabric and one weft thread in the bottom fabric. This is the case if one wishes to achieve the three-shot weave in two working cycles or two runs of the weaving machine. For a known two-shot weave it is expedient, for example, first to insert no weft thread at all in the top fabric and two weft threads in the bottom fabric simultaneously, and then to insert two weft threads in the top fabric and no weft thread in the bottom fabric. In this process the top or bottom weft insertion device is switched off in each case.
In this known process, for a first shot the shed with ground warp thread course is presented for single or no insertion in the top fabric and double insertion in the bottom fabric, and for a second shot the ground warp thread course is presented for double weft insertion in the top fabric and single or no weft insertion in the bottom fabric.
From this presentation of the warp thread course for both cases it can be deduced that the binding warp for a first shot, for example, has to form a small shed opening for one gripper, and for the second shot a large or double shed opening for two grippers. Moreover, the bisector of these small and large shed openings does not coincide, so that this known separating roller arrangement is not sufficient to bring binding warp thread layers to the same tension. One layer becomes tensioned, the other becomes slack, in such a way that weaving becomes impossible.
For the top fabric the bisector plane of the binding warp thread planes runs from fabric edge until it makes contact above the top separating roller for a first shot cycle. For the top fabric the bisector plane of the binding warp thread planes runs from the fabric edge until it is far below the first separating roller for the second shot. For the bottom fabric a similar arrangement can be made.